JWT signature compute in c#

jwt.cs

// From stackoverflow and adapted to unusure it makes sense with our data
// -- https://stackoverflow.com/questions/38725038/c-sharp-how-to-verify-signature-on-jwt-token

void Main()
{
	var jwt = "some-jwt";
	
	var segments = jwt.Split('.');
	var decoded = segments.Select(s => System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(s)));
	
	// Cleaner	
	var headerAndPayload = jwt.Substring(0, jwt.LastIndexOf('.'));
	Console.WriteLine(headerAndPayload);
	
	// Segmented...	
	// var headerAndPayload1 = String.Join(".", segments.Take(2));
	// Console.WriteLine(headerAndPayload1);
	
	var jwtSignatureSecret = "secret";
	var bytesToSign = Encoding.UTF8.GetBytes(headerAndPayload);
	var hmacAlg = new System.Security.Cryptography.HMACSHA256(Encoding.UTF8.GetBytes(jwtSignatureSecret));
	var hash = hmacAlg.ComputeHash(bytesToSign);

	Console.WriteLine("Expected: " + Base64UrlEncode(hash));
    Console.WriteLine("Actual  : " + segments.Last());
}

// from JWT spec
private static string Base64UrlEncode(byte[] input) {
    var output = Convert.ToBase64String(input);
    output = output.Split('=')[0]; // Remove any trailing '='s
    output = output.Replace('+', '-'); // 62nd char of encoding
    output = output.Replace('/', '_'); // 63rd char of encoding
    return output;
}